So-called nail plates are well known within the technique of joining different pieces of wood to one another. Such nail plates are usually made of a metal sheet which has a thickness of a few millimetres and in which flanges have been punched, which have been folded outwards so that they protrude from one main surface of the plate. The nail plates are used for joining in nodal points, where different pieces of wood meet in the same plane. In such joints, the main purpose is to absorb tensile stress in the longitudinal direction of the pieces of wood, and nail plates are well suited for this purpose.
It is already known from GB 2 322 425 that a joint and a pallet where two pallet elements not located in the same plane are connected surface against surface by a combination of a nail plate between the pallet elements and nails which are completely driven through at least one of the pallet elements, penetrate through the nail plate and a distance into the other pallet element. The purpose of the nail plate is in this case only to increase the shearing strength relative to a corresponding joint using only nails and not actually to connect the pallet elements with one another. However, in the same patent specification an alternative embodiment is disclosed where the punched-out flanges are folded outwards in opposite directions so that the flanges protrude from the two main surfaces of the plate. When placing such a nail plate between two pieces of wood, the nail plate, of course, also has a certain uniting effect on the pieces of wood, but the nail plate is in this case combined with through-nailing through both the nail plate and the pieces of wood. A common feature of all nail plates in this patent specification is that flanges are punched out from only certain portions of the plates, while others are left unperforated and reserved for the through nails. Such combined joints with nails as well as nail plates most likely obtain sufficient strength. However, it is time-consuming to produce them and once the pallet, or some other product that is connected in the same manner, is to be either discarded or mended, it is extremely difficult to dismantle them. When discarding, the parts included should as a rule for environmental reasons be divided into wood material for burning and metal for recycling, and it may be difficult to make this separation with a reasonable time expenditure since nails and nail plates can be wedged very tightly in one another. When mending and replacing separate parts of a pallet, it may for the same reasons be difficult to separate the parts without also breaking the parts that are to be kept. Naturally, also the total perforation of the pieces of wood on the one hand by conventional nails and, on the other, by the spikes of the nail plates increases the risk of the wood material already cracking during the joining.